/// <summary>
/// Updates the extension.
/// </summary>
/// <typeparam name="T">The type of extension.</typeparam>
/// <param name="elementName">Name of the element (null means use type name).</param>
/// <param name="value">The value.</param>
public void UpdateExtension <T>(XmlQualifiedName elementName, object value)
{
Utils.UpdateExtension <T>(ref m_extensions, elementName, value);
}